So I am working on taking the plunge and buying a fifth wheel, having sold my TT. My F150 is down the road and I have been truck shopping. Looking at 3-4 year old diesels, I find the price difference between a 2500 and 3500 is minimal. My instinct says to go for the bigger one, but what am I sacrificing in ride, mileage, maneuverability, etc? I am looking strictly at extended cab long bed 4X4's as we do enjoy four wheeling in the high country and I don't want to need a city block to turn around in. I am looking at trailers from 28'-30', with empty weight of 7580 and a gross of 15,000. Great site with lots of helpful folks! Lovin' it!

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If you are looking at 5th wheels, a 15,000 GVWR RV at capacity will have a pin weight of ~3,000 lbs (~20% of GVW). This weight is carried by the truck and counts against the truck's GVWR. Although a 3/4 ton and a 1 ton SRW truck might have the same GCWR, the 1 ton SRW truck will have a higher GVWR, and a 1 ton dually will have an even higher GVWR.

When evaluating the tow vehicle for use with a 5th wheel, it's just as important to determine how much weight the truck can carry as it is to determine how much weight the truck can the truck can pull. A typical 3/4 ton might have a GVWR of 8,800 to 9,200 lbs, a 1 ton SRW might have a GVWR of 9,900 lbs and a 1 ton dually might be around 11,500 lbs. For illustration, if the trucks above weigh around 7,500 lbs with driver, passengers, cargo, hitch, accessories, full fuel tank(s), etc. (my truck weighs 7,680 as an example), then the trucks could carry a pin weight as follows:

3/4 ton = 9,200 - 7,500 = 1,700 lbs

1 ton SRW = 9,900 - 7,500 = 2,400 lbs

1 ton dually = 11,500 - 7,500 = 4,000 lbs

In your case, you obviously need to plug in actual numbers for the particular trucks and RVs you're considering to determine how much truck you need from a pin weight perspective.

The "how much will it pull" calculation is the truck's laden curb weight (the 7,500 lb figure in the example above) subtracted from the truck's GCWR. This will be substantially less than the manufacturer's "marketing fluff" trailer tow rating which is calculated by subtracting the curb weight of a base truck with only a 150 lb driver from the truck's GCWR.

Wow, thanks for the detailed and informative reply. There really is a lot to this decision, one not to take lightly!

Reading around these forums, the legality of your tow setup comes up a lot.
I truly do not see myself ever loading the trailer to max GVW, that's a lot of gear. But if you have an accident, do they look at your actual weight or the maximum allowable weights?

I gather from what you said, the dually would be the better choice for the trailer I am looking at. But boy does that put a crimp in what I can four wheel on.

A compromise can be made.
I have an F350 with meats that I take into sand but also need to tow with. The list of trailers I can tow with is not as unlimited as if it wasn't lifted or if it was a dually. But I have never needed a 40' toyhauler anyway. Watch the weight rating, pack the trailer accordingly - you don't need to overload, and you do have some good choices.

Reading around these forums, the legality of your tow setup comes up a lot.

There is a lot of FUD mongering based on false information, myth, or dreams. Don't let it get you.

In regard to weight, keep in mind that the specs are ratings and not limits. They are a guide and the only significant legal issue is in the commercial realm where it is a tax and license (income) source for the state.

You should know the why - for instance, tire and wheel weight ratings are most important as a failure there can be catastrophic. Axle ratings tend to be more about wear and tear and maintenance. Combined vehicle ratings are wild guesses.

Anytime anyone starts spouting about dangerous circumstances or legalities, ask for citation and reference - and then read carefully. You can also just look at what you see on the road or in a campground to get an idea of just how far people take things. Check your insurance policy as well for exceptions and conditions as that will tell you what they think is important.

Let's not start a fight here. Rusty has made a good presentation of the facts. There is a large group of truck owners that seem to seek safety in numbers and console one another about towing beyond the manufactures ratings.

The manufacturers have engineers that design trucks to meet certain demands and they do include a safety factor in the design. Like a large number of things I deal with, there are safety factors to allow for relatively safe operation of the equipment to minimize danger to property and life.

As a responsible engineer, I will not knowingly design any piece of equipment for operation outside of the manufacturers ratings without the manufacturer provideing a me a letter stating operation out side of the ratings.

In order for each person to evaluate towing ratings and weights, we present the know facts and make sure they are understood. This way, the person towing, can make an educated decision about their vehicle and trailer and not base it on someone simply stating, that they do fine. Every ones towing needs are different.

Interesting response to a warning about FUD mongering and myths - it is almost impossible to discuss these things rationally as they seem to bring out the mudslingers. I wish it were not so. The response should be a caution to anyone listening to advice presented in this media as often those with the most unreliable assertions hold them most tightly.

I described an order of concern and provided the basic reasons for it - the idea being, as Ken noted, to help people understand the ratings in order to be able to make better informed decisions for themselves. I was not telling anyone what to do but rather suggesting ideas that I think should be considered.

Why do I think the combined weight rating is a wild guess?

The reason is that it is an attempt to accommodate many factors that are not known when the number is created and it is based on a number of assumptions which may or may not be valid. On some vehicles such a rating is offered for reasons that have nothing to do with towing factors (many mini-vans fit into this category). An example of a 'loose' factor that used to be seen with 'adjustments' was trailer frontal area - but even that assumes a particular rigging and set of environmental factors.

Any engineer worthy of his salt knows that measurements have consideration for accuracy and precision and any engineering specification must be considered in light of the defined circumstance in which it was presented and the purpose it was intended to serve.

I think it is also hubris to undertake a "we present the facts" attitude. The greatest benefit of these forums is from folks who will share experiences, share what they find and learn, suggest new ideas to think about, and receive in the same measure. I think this should be a forum of mutual discovery through discussion rather than source of lectures from someone who thinks they know all the facts someone else needs to have to guide their life.

Didn't know my questions would elicit such a spirited discussion. Obviously there's lots of opinions on this subject.

I am trying back into this. I've pretty much narrowed my trailer choices down and am trying to figure out how much truck I need to pull it safely.

The actual UVW of the larger of the two rigs I am looking at is 10,550lbs. Water capacity is 593lbs, assuming 2000lbs of gear, empty grey and black tanks, total is 13,143.

I truly do not envision ever running with full water and full waste tanks, so I think 13,143 is a pretty realistic number . 20% of that is 2628lbs. Using RustyJC's numbers (thanks Rusty!) a 3/4 ton is out of it's league, a SRW 1 ton is barely over. Having flown airplanes for many years I am very familier and comfortable with the concept of trading off payload for fuel. Just because the trailer is rated to 15,000lbs I am not going to load it up that heavy.

Today I saw an F250SD diesel going through town pulling at least a 36' Hitchhiker. You see combinations like that all over. What I am proposing pulling is actually on the small end of the 5'r spectrum. I am doing a balancing act, like everyone, wanting 4X4 capability, mileage, maneuverability, smoother ride. 1 tons are harder to find than 3/4 ton units, but if that's what is necessary I will hold out for that. But I don't want more truck than I need.

cobikeman
You won't often hear someone say they have too much TV, but many complain about handling, stopping and/or big trucks pushing them around. I feel much more comfortable with the 3500 dulley than I did with the 250 CTD.
If you want to go to the trouble, do a search on my posts and you will find a TV report about a F250 towing a 3axle 5er that didn't turn out pretty.

In 3rd gen Dodges, anyway, the difference between a 2500 and a SRW 3500 is a set of overload springs in the rear, cab lights on the earlier 3rd gens, and the numbers on the weight tag on the door.

I ran a 3500 SRW with a 30' toyhauler with GVWR of 12k. Loaded I was generally under 11k, and under all of the truck's ratings. If I were to run with tanks full and garage empty, though, I'd probably be over my rear axle rating.

When I decided to get a big one, I sold the SRW and got a dually. Before I got a big 5th wheel I did use the dually with the 30' one. The SRW handled it safely, but towing it with the dually was much more relaxing. On a narrow uneven mountain road it is just more stable.

After getting used to it I can get my dually around in a parking lot, drive through, or downtown parking just fine.

After towing with both, as long as I have a 5th wheel I will always have a dually.

As far as going fourbyfouring, I never really took the SRW out for that kind of stuff much anyway. With the price of a loaded diesel pickup these days, personally if I felt the need to go off road (more than I do on quads) I'd snag a used jeep or something...

I see someone else gave details of what I wanted to say so I'll just point out that in another forum there is a member who's sig file says "There is no replacement for displacement" and contains a photo of HIS tow vehicle........ A Peterbuilt Semi Tractor

The moral is this, when it comes to tow vehicles. there are many out there that frankly are too small for the job. I've seen several truck trailer combos that frankly scare me.

I"ve never seen a tow vehicle too large to do the job.. Now.. I do admit I've seen a few that were big enough to make me laugh.. but never one that was too big to do the job.

Kind of funny watching a Peterbuilt towing a walk-behind size Ditch Witch (I saw that one, I also walked beside the Witch assisting the guy walking behind, we got the ditch dug, yes, one of the many jobs I've done in my life is ditch digging I did not get paid for that one though)

There seems to be a trend among those with really big and heavy 5th wheels to tow with a modified class 8 tractor. It does seem to make sense in that a tractor with a few hundred thousand miles can be had for not much more than a new loaded dually. Cut the frame down a bit, use just the rear drive axle, and a person could end up with something that will last for many hundreds of thousands of miles. Suddenly that heavy 5th wheel would seem pretty light (probably about the weight of an empty semi trailer).